In several communications systems the data to be transmitted is compressed so that the available bandwidth is used more efficiently. For example, the Moving Pictures Experts Group (MPEG) has promulgated several standards relating to digital data delivery systems. The first, known as MPEG-1 refers to ISO/IEC standards 11172 and is incorporated herein by reference. The second, known as MPEG-2, refers to ISO/IEC standards 13818 and is incorporated herein by reference. A compressed digital video system is described in the Advanced Television Systems Committee (ATSC) digital television standard document A/53, and is incorporated herein by reference.
The above-referenced standards describe data processing and manipulation techniques that are well suited to the compression and delivery of video, audio and other information using fixed or variable length digital communications systems. In particular, the above-referenced standards, and other "MPEG-like" standards and techniques, compress, illustratively, video information using intra-frame coding techniques (such as run-length coding, Huffman coding and the like) and inter-frame coding techniques (such as forward and backward predictive coding, motion compensation and the like). Specifically, in the case of video processing systems, MPEG and MPEG-like video processing systems are characterized by prediction-based compression encoding of video frames with or without intra- and/or inter-frame motion compensation encoding.
Information distribution systems utilizing information streams conforming to the above standards or subsets of the above standards are known. For example, an interactive digital video on demand (VOD) service known as the OnSet.TM. system is manufactured by DIVA Systems Corporation of Menlo Park, Calif. The OnSet.TM. system distributes audio-visual information to individual subscribers utilizing MPEG-like information streams. The OnSet.TM. system also allows subscribers to interactively control the delivery of audio-visual information using consumer-friendly commands, such as fast-forward (FF), rewind (REW), pause (PAUSE), play (PLAY) and the like.
The OnSet.TM. system utilizes additional information streams to provide a so-called movie information screen (MIS) feature to subscribers. The MIS feature comprises a substantially motionless image, such as from a movie or other audio-visual program, displayed on a subscriber's display device. The MIS, which is typically accompanied by a related audio track, functions as a "barker" tending to induce impulse subscriber purchases of the movie or other audio-visual program.
Unfortunately, existing methods for generating MIS information streams disadvantageously require extensive encoding of video information to produce well-behaved bitstreams, i.e., bitstreams that do not cause decoder buffer underflow or overflow. For example, an MIS information stream generated by repeatedly encoding an image will produce a well-behaved MIS bitstream at the cost of significant computational resources and time (e.g., two to 30 minutes to encode a two minute MIS display or presentation).
Therefore, it is seen to be desirable to provide a rapid, computationally efficient method for generating well-behaved MIS information streams.